Objective To explore the diagnosis and treatment of severe type Ⅰ herpes virus (HSV-1) pneumonia patients with normal immune function. Methods Four patients admitted to Ruijin Hospital of Shanghai Jiao Tong University School of Medicine from April 2021 to December 2021 who were diagnosed as severe HSV-1 pneumonia were enrolled, and their clinical data and the relevant domestic and foreign literatures were reviewed. All 4 patients were male, and their age was between 72 and 89 years. Results The main symptoms were fever, cough, expectoration (some patients had bloody sputum), asthma and dyspnea. All patients developed severe type Ⅰ respiratory failure. The infection indicators of all four patients increased, along with a relative decrease in lymphocyte counts, and a significant increase in CD3, CD4, and CD8 absolute counts after treatment. HSV-1 was detected in respiratory specimen using metagenomic next generation sequencing (mNGS) in them. After receiving early antiviral and hormonal anti-inflammatory therapy and respiratory support, the conditions in all four patient improved, and three of them were cured and discharged from the hospital. A total of 26 cases of HSV-1 pneumonia with low immunity and 3 cases with normal immune function were found in the literature, and most of cases lacked specific clinical symptoms and signs. As anti-bacterial or fungal treatment failed, most of them received the etiological examination of alveolar lavage fluid and was confirmed HSV-1 infection. The patients were given acyclovir antiviral therapy, and some patients also got hormone therapy. Three cases with normal immune function and 22 of 26 cases with low immunity showed improved condition, while 4 cases died. Conclusions The clinical symptoms of severe HSV-1 pneumonia lacked specificity and the diagnosis was difficult in elderly patients. mNGS of respiratory secretions combined with routing laboratory tests is helpful to identify the pathogen and make early diagnosis of the disease. The disease can be effectively treated through early recognition of the disease, administration of antiviral drugs, and a short-term treatment of glucocorticoid.